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PubMed2003

The phylogenetic position of red algae revealed by multiple nuclear genes from mitochondria-containing eukaryotes and an alternative hypothesis on the origin of plastids.

Red algae are one of the main photosynthetic eukaryotic lineages and are characterized by primitive features, such as a lack of flagella and the presence of phycobiliproteins in the chloroplast. Recent molecular phylogenetic studies using nuclear gene sequences suggest two conflicting hypotheses (monophyly versus non-monophyly) regarding the relationships between red algae and green plants. Although kingdom-level phylogenetic analyses using multiple nuclear genes from a wide-range of eukaryotic lineages were very recently carried out, they used highly divergent gene sequences of the cryptomonad nucleomorph (as the red algal taxon) or incomplete red algal gene sequences. In addition, previous eukaryotic phylogenies based on nuclear genes generally included very distant archaebacterial sequences (designated as the outgroup) and/or amitochondrial organisms, which may carry unusual gene substitutions due to parasitism or the absence of mitochondria. Here, we carried out phylogenetic analyses of various lineages of mitochondria-containing eukaryotic organisms using nuclear multigene sequences, including the complete sequences from the primitive red alga Cyanidioschyzon merolae. Amino acid sequence data for two concatenated paralogous genes (alpha- and beta-tubulin) from mitochondria-containing organisms robustly resolved the basal position of the cellular slime molds, which were designated as the outgroup in our phylogenetic analyses. Phylogenetic analyses of 53 operational taxonomic units (OTUs) based on a 1525-amino-acid sequence of four concatenated nuclear genes (actin, elongation factor-1alpha, alpha-tubulin, and beta-tubulin) reliably resolved the phylogeny only in the maximum parsimonious (MP) analysis, which indicated the presence of two large robust monophyletic groups (Groups A and B) and the basal eukaryotic lineages (red algae, true slime molds, and amoebae). Group A corresponded to the Opisthokonta (Metazoa and Fungi), whereas Group B included various primary and secondary plastid-containing lineages (green plants, glaucophytes, euglenoids, heterokonts, and apicomplexans), Ciliophora, Kinetoplastida, and Heterolobosea. The red algae represented the sister lineage to Group B. Using 34 OTUs for which essentially the entire amino acid sequences of the four genes are known, MP, distance, quartet puzzling, and two types of maximum likelihood (ML) calculations all robustly resolved the monophyly of Group B, as well as the basal position of red algae within eukaryotic organisms. In addition, phylogenetic analyses of a concatenated 4639-amino-acid sequence for 12 nuclear genes (excluding the EF-2 gene) of 12 mitochondria-containing OTUs (including C. merolae) resolved a robust non-sister relationship between green plants and red algae within a robust monophyletic group composed of red algae and the eukaryotic organisms belonging to Group B. A new scenario for the origin and evolution of plastids is suggested, based on the basal phylogenetic position of the red algae within the large clade (Group B plus red algae). The primary plastid endosymbiosis likely occurred once in the common ancestor of this large clade, and the primary plastids were subsequently lost in the ancestor(s) of the Discicristata (euglenoids, Kinetoplastida, and Heterolobosea), Heterokontophyta, and Alveolata (apicomplexans and Ciliophora). In addition, a new concept of "Plantae" is proposed for phototrophic and nonphototrophic organisms belonging to Group B and red algae, on the basis of the common history of the primary plastid endosymbiosis. The Plantae include primary plastid-containing phototrophs and nonphototrophic eukaryotes that possibly contain genes of cyanobacterial origin acquired in the primary endosymbiosis.

Cell Nucleus↗
PubMed2006

Photoreduction of chromium(VI) in the presence of algae, Chlorella vulgaris.

In this thesis, the photochemical reduction of hexavalent chromium Cr(VI) in the presence of algae, Chlorella vulgaris, was investigated under the irradiation of metal halide lamps (lambda = 365 nm, 250 W). The affecting factors of photochemical reduction were studied in detail, such as exposure time, initial Cr(VI) concentration, initial algae concentration and pH. The rate of Cr(VI) photochemical reduction increased with algae concentration increasing, exposure time increasing, initial Cr(VI) concentration decreasing and the decrease of pH. When pH increased to 6, the rate of Cr(VI) photochemical reduction nearly vanished. When initial Cr(VI) concentration ranged from 0.4 to 1.0 mg L(-1) and initial algae concentration ranged from ABS(algae) (the absorbency of algae) = 0.025 to ABS(algae) = 0.180, According to the results of kinetic analyses, the kinetic equation of Cr(VI) photochemical reduction in aqueous solution with algae under 250 W metal halide lamps was V0 = kC(0)(0.1718)A(algae)(0.5235) (C0 was initial concentration of Cr(VI); A(algae) was initial concentration of algae) under the condition of pH 4.

Biodegradation, Environmental↗
PubMed1997

Role of Hydrophobicity in Adhesion of the Dissimilatory Fe(III)-Reducing Bacterium Shewanella alga to Amorphous Fe(III) Oxide.

The mechanisms by which the dissimilatory Fe(III)-reducing bacterium Shewanella alga adheres to amorphous Fe(III) oxide were examined through comparative analysis of S. alga BrY and an adhesion-deficient strain of this species, S. alga RAD20. Approximately 100% of S. alga BrY cells typically adhered to amorphous Fe(III) oxide, while less than 50% of S. alga RAD20 cells adhered. Bulk chemical analysis, isoelectric point analysis, and cell surface analysis by time-of-flight secondary-ion mass spectrometry and electron spectroscopy for chemical analysis demonstrated that the surfaces of S. alga BrY cells were predominantly protein but that the surfaces of S. alga RAD20 cells were predominantly exopolysaccharide. Physicochemical analyses and hydrophobic interaction assays demonstrated that S. alga BrY cells were more hydrophobic than S. alga RAD20 cells. This study represents the first quantitative analysis of the adhesion of a dissimilatory Fe(III)-reducing bacterium to amorphous Fe(III) oxide, and the results collectively suggest that hydrophobic interactions are a factor in controlling the adhesion of this bacterium to amorphous Fe(III) oxide. Despite having a reduced ability to adhere, S. alga RAD20 reduced Fe(III) oxide at a rate identical to that of S. alga BrY. This result contrasts with results of previous studies by demonstrating that irreversible cell adhesion is not requisite for microbial reduction of amorphous Fe(III) oxide. These results suggest that the interaction between dissimilatory Fe(III)-reducing bacteria and amorphous Fe(III) oxide is more complex than previously believed.

Journal Article↗
PubMed2001

Allelopathic effect of Acorus tatarinowii upon algae.

Besides competing with algae for light and mineral nutrients (i.e. N, P, etc.), the root system of Acorus tatarinowii excretes some chemical substances, which injure and eliminate alga cells, to inhibit the growth of the algae. When the algae cells were treated in "A. tatarinowii water", some of the chlorophyll a were destroyed and the photosynthetic rate of algae decreased markedly and the ability of alga cells to deoxidize triphenyltetrazolium chloride (TTC) reduced greatly. Then alga cells turned from bright red to bluish green under fluorescence microscope. These showed that the allelopathic effects of A. tatarinowii on algae were obvious and planting A. tatarinowii can control some green algae. The experiment on the extractions of the secretions of the root system showed that the inhibitory effect had a concentration effect. If the concentration of the root secretion was below 30 microliters/disc, the inhibitory rate was negative; if it was over 45 microliters/disc, the inhibitory rate was positive. This proved that the influence of the root secretion on the same acceptor was a kind of concentration effect. When the concentration of the root secretion was low, it promoted the growth of algae; when the concentration reached a definite threshold value, it restrained the growth of algae. In present case, the threshold value was between 30 microliters/disc and 45 microliters/disc.

Acorus↗
PubMed1950

Photosynthetic action spectra of marine algae.

A polarographic oxygen determination, with tissue in direct contact with a stationary platinum electrode, has been used to measure the photosynthetic response of marine algae. These were exposed to monochromatic light, of equal energy, at some 35 points through the visible spectrum (derived from a monochromator). Ulva and Monostroma (green algae) show action spectra which correspond very closely to their absorption spectra. Coilodesme (a brown alga) shows almost as good correspondence, including the spectral region absorbed by the carotenoid, fucoxanthin. In green and brown algae, light absorbed by both chlorophyll and carotenoids seems photosynthetically effective, although some inactive absorption by carotenoids is indicated. Action spectra for a wide variety of red algae, however, show marked deviations from their corresponding absorption spectra. The photosynthetic rates are high in the spectral regions absorbed by the water-soluble "phycobilin" pigments (phycoerythrin and phycocyanin), while the light absorbed by chlorophyll and carotenoids is poorly utilized for oxygen production. In red algae containing chiefly phycoerythrin, the action spectrum closely resembles that of the water-extracted pigment, with peaks corresponding to its absorption maxima (495, 540, and 565 mmicro). Such algae include Delesseria, Schizymenia, and Porphyrella. In the genus Porphyra, there is a series P. nereocystis, P. naiadum, and P. perforata, with increasingly more phycocyanin and less phycoerythrin: the action spectra reflect this, with increasing activity in the orange-red region (600 to 640 mmicro) where phycocyanin absorbs. In all these red algae, photosynthesis is almost minimal at 435 mmicro and 675 mmicro, where chlorophyll shows maximum absorption. Although the chlorophylls (and carotenoids) are present in quantities comparable to the green algae, their function is apparently not that of a primary light absorber; this role is taken over by the phycobilins. In this respect the red algae (Rhodophyta) appear unique among photosynthetic plants.

Chlorophyll↗
PubMed1999

Evaluation of the contamination of marine algae (Seaweed) from the St. Lawrence River and likely to be consumed by humans.

The goal of the study was to assess the contamination of marine algae (seaweeds) growing in the St. Lawrence River estuary and Gulf of St. Lawrence and to evaluate the risks to human health from the consumption of these algae. Algae were collected by hand at low tide. A total of 10 sites on the north and south shores of the St. Lawrence as well as in Baie des Chaleurs were sampled. The most frequently collected species of algae were Fucus vesiculosus, Ascophyllum nodosum, Laminaria longicruris, Palmaria palmata, Ulva lactuca, and Fucus distichus. Alga samples were analyzed for metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn), iodine, and organochlorines. A risk assessment was performed using risk factors (e.g., RfD of the U.S. EPA, ADI of Health Canada, etc.). In general, concentrations in St. Lawrence algae were not very high. This was especially true for mercury and the organochlorines, concentrations of which were very low or below detection limits. Consequently, health risks associated with these compounds in St. Lawrence algae were very low. Iodine concentration, on the other hand, could be of concern with regard to human health. Regular consumption of algae, especially of Laminaria sp., could result in levels of iodine sufficient to cause thyroid problems. For regular consumers, it would be preferable to choose species with low iodine concentrations, such as U. lactuca and P. palmata, in order to prevent potential problems. Furthermore, it would also be important to assess whether preparation for consumption or cooking affects the iodine content of algae. Algae consumption may also have beneficial health effects. Scientific literature has shown that it is a good source of fiber and vitamins, especially vitamin B12.

Environmental Exposure↗
PubMed1995

Biotransformation of benzo[a]pyrene and other polycyclic aromatic hydrocarbons and heterocyclic analogs by several green algae and other algal species under gold and white light.

This laboratory has shown that the metabolism of benzo[a]pyrene (BaP), a carcinogenic polycyclic aromatic hydrocarbon (PAH), by a freshwater green alga, Selenastrum capricornutum, under gold light proceeds through a dioxygenase pathway with subsequent conjugation and excretion. This study was undertaken to determine: (1) the effects of different light sources on the enzymatic or photochemical processes involved in the biotransformation of BaP over a dose range of 5-1200 mg/l; (2) the phototoxicity of carcinogenic PAHs and mutagenic quinones to a green alga; (3) the ability of other algal systems to metabolize BaP. Cultures were exposed to different doses of BaP for 2 days at 23 degrees C under gold, white or UV-A fluorescent light on a diurnal cycle of 16 h light, 8 h dark. Under gold light, metabolites of BaP produced by Selenastrum capricornutum were the dihydrodiols of which the 11,12-dihydrodiol was the major metabolite. Under white light, at low doses, the major metabolite was the 9,10-dihydrodiol. With increasing dose, the ratio of dihydrodiols to quinones decreased to less than two. With increasing light energy output, from gold to white to UV-A in the PAH absorbing region, BaP quinone production increased. Of other carcinogenic PAHs studied, only 7H-dibenz[c,g]carbazole was as phototoxic as BaP while 7,12-dimethylbenz[a]anthracene, dibenz[a,j]acridine and non-carcinogenic PAHs, anthracene and pyrene, were not phototoxic. The 3,6-quinone of BaP was found to be highly phototoxic while quinones that included menadione, danthron, phenanthrene-quinone and hydroquinone were not. The data suggest that the phototoxicity of BaP is due to photochemical production of quinones; the 3,6-quinone of BaP is phototoxic and is probably the result of the production of short lived cyclic reactive intermediates by the interaction of light with the quinone. Lastly, only the green algae, Selenastrum capricornutum, Scenedesmus acutus and Ankistrodesmus braunii almost completely metabolized BaP to dihydrodiols. The green alga Chlamydomonas reinhardtii, the yellow alga Ochromonas malhamensis, the blue green algae Anabaena flosaquae and euglenoid Euglena gracilis did not metabolize BaP to any extent. The data indicate that algae are important in their ability to degrade PAHs but the degradation is dependent on the dose of light energy emitted and absorbed, the dose of PAHs to which the algae are exposed, the phototoxicity of PAHs and their metabolite(s) and the species and strain of algae involved. All of these factors will be important in assessing the degradation and detoxification pathways of recalcitrant PAHs by algae.

Anabaena↗
PubMed1982

Viruses of symbiotic Chlorella-like algae isolated from Paramecium bursaria and Hydra viridis.

We previously reported that isolation of symbiotic Chlorella-like algae from the Florida strain of Hydra viridis induced replication of a virus (designated HVCV-1) in the algae. We now report that isolation of symbiotic Chlorella-like algae from four other sources of green hydra and one source of the protozoan Paramecium bursaria also induced virus synthesis. Algae from one of these hydra contained a virus identical to HVCV-1 (based on its rate of sedimentation, buoyant density, reaction to HVCV-1 antiserum, and DNA restriction fragments) whereas algae from the other three hydra contained another similar, but distinct, virus (designated HVCV-2). The virus from the paramecium algae (designated PBCV-1) was distinct from both HVCV-1 and HVCV-2. The symbiotic algae in the hydra could also be distinguished ultrastructurally. Chloroplasts of both algae that produced HVCV-1 lacked a pyrenoid whereas chloroplasts of the other three symbiotic algae contained pyrenoids. Since all symbiotic eukaryotic algae we have examined have had virus, a potential viral role in symbiosis is suggested.

Journal Article↗
PubMed2003

[A review on algae ecology in wetland].

The research advance in algae ecology in wetland was introduced in this paper, which included the algae population structure and its function, and the algae productivity and its affecting factors. Almost all kinds of algae occurred in wetland, including four assemblages: epipelon, epiphyton, metaphyton and phytoplankton, among which, diatom, green and blue algae were the predominant species. Algae were the fundamental players in the physical, chemical and biological processes that characterized wetland ecosystems. Most obvious was their role as primary producers and their place in the wetland food web. Algae were an important food resource for herbivores, and contributed to wetland nutrient cycle as the sources of dissolved organic matter and N. They could also be used as biomarkers for monitoring environment pollution. The affecting factors on algae's productivity were hydraulic factor, nutrition, temperature, illumination, herbivores and some other animals, and so on. Because of their functions in wetland, future research on algae in wetland should expand our knowledge of the environmental controls on algal biomass, productivity, and species composition in wetlands with particular in areas for which knowledge was incomplete. Included among these, may be a detailed evaluation of the proportionate contributions by epipelon, epiphyton, metaphyton, and phytoplankton to food web dynamics in wetlands, and a further study of the genetic technique in controlling hazardous algae.

Ecology↗
PubMed2006

Analysis of fluorescence from algae fossils of the Neoproterozoic Doushantuo formation of China by confocal laser scanning microscope.

Chinese algae fossils can provide unique information about the evolution of the early life. Thin sections of Neoproterozoic algae fossils, from Guizhou, China, were studied by confocal laser scanning microscopy, and algae fossils were fluorescenced at different wavelengths when excited by laser light of 488 nm, 476 nm, and 568 nm wavelength. When illuminated by 488 nm laser light, images of the algae fossils were sharper and better defined than when illuminated by 476 nm and 568 nm laser light. The algae fossils fluoresce at a wide range of emission wavelengths. The three-dimensional images of the fluorescent algae fossils were compared with the transmission images taken by light microscope. We found that the fluorescence image of the confocal laser scanning microscope in a single optical section could pass for the transmission image taken by a light microscope. We collected images at different sample depths and made a three-dimensional reconstruction of the algae fossils. And on the basis of the reconstruction of the three-dimensional fluorescent images, we conclude that the two algae fossils in our present study are red algae.

Cell Wall↗
PubMed2006

Survival of blue-green and green algae under stress conditions.

Terrestrial blue-green algae Scytonema millei, Phormidium bohneri and Lyngbya mesotricha survived to 100 % at atmospheric temperatures of 5-36 degrees C and relative humidity 55-100 % in rainy, winter and spring seasons but the survival was 15-25 % in summer when atmospheric temperature reached 48 degrees C and relative humidity was < or =23 %. Microcoleus chthonoplastes maximum survival was =80 % in rainy season followed by a decrease to =1/2 and 1/4 level in winter and spring, respectively; it disappeared in summer but a few cells and/or trichomes enclosed within sheath may be surviving sticking to soil, not evident microscopically, since the population reappeared at the same place with the onset of rain. Terrestrial green alga Rhizoclonium crassipellitum survived only in spring and died at the onset of summer without forming any dormant cell and/or reproductive structure. Only P. bohneri survived better and longer under submerged conditions in liquid medium than air-exposed on moist soil surface in the culture chamber, while the other algae fared almost equally or slightly better air-exposed on moist soil surface (or even on 2 % agarized medium) than when suspended in liquid medium, indicating that air exposure rather than submerged conditions was needed for most of the terrestrial algae to survive. Water stress imposed on growing algae either on high-agar-solid media or in 0.2-0.6 mol/L NaCl liquid media in the culture chamber reduced vegetative survival in all; it resulted in death without any dormant cell remaining. When stored in desiccators over fused CaCl2, M. chthonoplastes died within 1/2 month, R. crassipellitum and L. mesotricha within 1 month, P. bohneri within 1/2 month, and S. millei not even within 1 1/2 month, indicating their survival pattern against atmospheric dryness to be wide; it also explained the M. chthonoplastes absence in summer and S. millei presence throughout the year. At increased atmospheric humidity the desiccation-sensitive algae (e.g., M. chthonoplastes) survived better than a desiccation-resistant alga (here S. millei). All algae survived considerable darkness (S. millei > 1 1/2 month; P. bohneri, M. chthonoplastes and R. crassipellitum >1 month, and L. mesotricha >1/2 month), and low light intensity of 2 and 10 micromol m(-2)s(-1) which explains their prolific growth in shady places. All algae were differently sensitive to wet heat (45 degrees C for 5-40 min) and to UV shock (0.96-3.84 kJ/m2).

Chlorophyta↗
PubMed2005

The mechanisms of potassium permanganate on algae removal.

The effect of potassium permanganate as preoxidant for algae-laden source water and the mechanism that it causes algae cells aggregation was investigated. Synthetic algae suspensions, prepared from lab-cultured Chodatella sp., were used for batch preoxidation and settling tests. In order to study the effect of water hardness on the function of permanganate, some algae suspensions were spiked with CaCl2 solution. Experiments with preformed MnO2 to look into its effect on algae cell aggregation were also conducted. The results show that preoxidation with potassium permanganate would promote the aggregation of algae cells, and this phenomenon was even more significant with the existence of hardness causing ion, calcium. In addition to incorporating its reducing product, MnO2, into algae floc, and increased its specific gravity, and therefore its settling velocity, permanganate may also induce the release of extracellular organic matters (EOM) from algae cell. Based on SEM observation, EOM probably enhanced the incorporation of MnO2 into algae floc. The role played by calcium ion in promoting the function of permanganate can be explained by charge neutralization and also bridging between negatively charged surfaces.

Calcium Chloride↗
PubMedDate not supplied

Biosorption with algae: a statistical review.

The state of the art in the field of biosorption using algae as biomass is reviewed. The available data of maximum sorption uptake (qmax) and biomass-metal affinity (b) for Cd2 +, Cu2 +, Ni2 +, Pb2 + and Zn2 + were statistically analyzed using 37 different algae (20 brown algae, 9 red algae and 8 green algae). Metal biosorption research with algae has used mainly brown algae in pursuit of treatments, which improve its sorption uptake. The information available in connection with multimetallic systems is very poor. Values of qmax were close to 1 mmol/g for copper and lead and smaller for the other metals. Metal recovery performance was worse for nickel and zinc, but the number of samples for zinc was very small. All the metals except lead present a similar affinity for brown algae. The difference in the behavior of lead may be due to a different uptake mechanism. Brown algae stand out as very good biosorbents of heavy metals. The best performer for metal biosorption is lead.

Adsorption↗
PubMed1999

Dietary marine algae (Schizochytrium sp.) increases concentrations of conjugated linoleic, docosahexaenoic and transvaccenic acids in milk of dairy cows.

Modification of milk fat to contain long-chain (n-3) fatty acids and increased concentrations of conjugated linoleic acid has potential for improving health of consumers. Natural modification of milk through nutritional manipulation of diets for dairy cows is preferable to post-harvest modification. The objectives of this study were to increase the concentrations of beneficial fatty acids in milk fat by feeding a diet rich in (n-3) fatty acids from algae to dairy cows. Cows were fed a control diet, a diet containing algae (Schizochytrium sp.) protected against ruminal biohydrogenation, or a diet containing unprotected algae for 6 wk. Feed intake and milk production were recorded daily. Milk samples were obtained weekly for analysis of milk composition and profile of fatty acids. Percentage of fat in milk of cows fed algae was lower (P < 0.01) than in milk from cows fed the control diet; however, energy-corrected milk production did not differ (P > 0.05). Inclusion of algae in diets decreased (P < 0.01) feed intake. Milk fat from cows fed algae contained greater (P < 0.01) concentrations of conjugated linoleic acid, (n-3) fatty acids (particularly docosahexaenoic acid), and transvaccenic acid. Concentrations of docosahexaenoic acid were greater (P < 0.01) in milk fat from cows fed protected algae compared to milk fat from cows fed unprotected algae. Milk fat from cows fed algae contained lower (P < 0.05) concentrations of total saturated fatty acids compared to cows fed the control diet. In conclusion, milk fat can be modified through nutritional management of dairy cows to provide more favorable fatty acids for consumers.

Animal Feed↗
PubMed2006

Settling characteristics of problem algae in the water treatment process.

The settling velocity or removal rates of problem algae in the water treatment process and their flocculants were measured with settling column (SETCOL) and fluorometric method. Our research who were centred on the algal density and shape affecting the settling. The settling velocities of large algae ranged from 0.1 cm/h to 2.6 cm/h, whereas those of small algae were below 1.0 cm/h. The settlings of algae in the stationary growth phase significantly increased and dead algae corresponded with the declining algae. The extent of deformation, which was expressed as the coefficient of form resistance of the algae had the great influences upon the settling. The most extreme deformed algae were needle-shaped ones like Synedra acus, which was known to be a problem in water treatment processes in Korea. Changes in the settling velocity of algae were correlated with algal volume and morphology rather than cell density.

Eukaryota↗
PubMed2002

Optical compartmentation of vegetating algae species as a basis for their growth-specific characterization.

BACKGROUND: The number of microalgal strains known to date is enormous and continuously growing, and their characterization accordingly requires quick and reliable methodologies. METHODS: Asynchronously growing logarithmic (3- and 6-day cultures) and stationary (9-day cultures) phase cell populations of two algae species that are difficult to distinguish microscopically (one Chlorella sp., C. vulgaris [c-27], and another that might belong to the same genus, SA-3 algae exsymbiotic from Paramecium bursaria) were characterized by means of flow cytometry (FCM). Forward light scatter (FSC) of algae was monitored in association with their 90 degrees side light scatter (SSC) and fluorescence of endogenous chlorophyll (FL3-height). RESULTS: Two-parameter FSC versus SSC and FSC versus FL3-height plots distinctly showed growth-specific compartmentation of algae into discrete cell subpopulations staying at a particular stage of the life cycle, and numbers of cells constituting these subpopulations could be quantitated. The growth pattern of C. vulgaris (c-27) differed substantially from that of SA-3 algae, particularly in the late-logarithmic (6-day) cultures. At this phase of growth, C. vulgaris (c-27) cells compartmentalized into three subpopulations, whereas SA-3 cells compartmentalized into two subpopulations. Different compartmentations of optical signals from late-logarithmic phase SA-3 algae and C. vulgaris (c-27) likely were caused by the differences in timing of the life cycle stages of these types of cells. CONCLUSIONS: Growth-specific compartmentation of vegetating microalgae by FCM provides a good basis for characterization of morphologically similar algae species. Because algae are also present in symbiotic relationships with other organisms, this tool might be of potential interest for the study of symbiosis mechanisms.

Cell Compartmentation↗
PubMed2001

Biliproteins and phycobilisomes from cyanobacteria and red algae at the extremes of habitat.

This review considers the properties of biliproteins from cyanobacteria and red algae that grow in extreme habitats. Three situations are presented: cyanobacteria that grow at high temperatures; a red alga that grows in acidic conditions at high temperature; and an Antarctic red alga that grows in the cold in dim light conditions. In particular, the properties of their biliproteins are compared to those from organisms from more usual environments. C-phycocyanins from two cyanobacteria able to grow at high temperatures are found to differ in their stabilities when compared to C-phycocyanin from mesophilic algae. They differ in opposite ways, however. One is more stable to dissociation than the mesophilic protein, and the other is more easily dissociated at low temperatures. The thermophilic proteins resist thermal denaturation much better than the mesophilic proteins. The most thermophilic cyanobacterium has a C-phycocyanin with a unique blue-shifted absorption maximum which does not appear to be part of the adaptation of the cyanobacterium to high temperature. The C-phycocyanin from the high-temperature red alga is able to resist dissociation better than mesophilic C-phycocyanins. Electron micrographs show the phycobilisomes of these algae. The Antarctic alga grows under ice at some distance down the water column. Its R-phycoerythrin has a novel absorption spectrum that gives the alga an improved ability to harvest blue light. This may enhance its survival in its light-deprived habitat.

Cold Temperature↗
PubMed1989

Closed and continuous algae cultivation system for food production and gas exchange in CELSS.

In CELSS (Controlled Ecological Life Support System), utilization of photosynthetic algae is an effective means for obtaining food and oxygen at the same time. We have chosen Spirulina, a blue-green alga, and have studied possibilities of algae utilization. We have developed an advanced algae cultivation system, which is able to produce algae continuously in a closed condition. Major features of the new system are as follows. (1) In order to maintain homogeneous culture conditions, the cultivator was designed so as to cause a swirl on medium circulation. (2) Oxygen gas separation and carbon dioxide supply are conducted by a newly designed membrane module. (3) Algae mass and medium are separated by a specially designed harvester. (4) Cultivation conditions, such as pH, temperature, algae growth rate, light intensity and quantity of generated oxygen gas are controlled by a computer system and the data are automatically recorded. This equipment is a primary model for ground experiments in order to obtain some design data for space use. A feasibility of algae cultivation in a closed condition is discussed on the basis of data obtained by use of this new system.

Biomass↗